American political polarization

These last two weeks my GOV 330 class has been examining the issue of political polarization in the United States. We looked at public opinion surveys, congressional voting patterns, and a number of studies on the subject. We learned that:

Americans are polarized in their views of the political parties and political candidates. Republicans don’t like the Democratic Party or Democratic candidates and Democrats don’t much care for the Republican Party or Republican candidates.

Interestingly, Americans are not very polarized in terms of their policy preferences. That is, the average Democrat and the average Republican in the U.S. are much closer to each other in terms of their stands on issues than they might suspect. They agree more often than they disagree and there is more common ground between them than distant chasms.

American are better sorted than they used to be. Through the 1950s-1980s, it was common to find liberal Republicans and conservative Democrats. Through the 1990s and 2000s, however, most liberal Republicans became Democrats and most conservative Democrats became Republicans. Thus it appears that polarization has increased simply because Democrats and Republicans are now more ideologically homogenous than they used to be, even though individual-level policy preference changes have been on a much smaller scale.